(RTTNews) - The European Union has slammed Iran with additional sanctions, the fourth punitive measure on the Islamic Republic within a week.

President Mahmoud Ahmadinejad's continued defiance to international calls to wind up its nuclear enrichment program has already cost the country heavily, as the United Nations last week placed its fourth set of sanctions on Iran, while Australia imposed Tuesday new sanctions on an Iranian bank, a shipping company, as well as a man connected to a construction firm owned by the Islamic Revolutionary Guard Corps.

Wednesday, the United States added Iranian individuals and firms to a blacklist.

European leaders, who have gathered in Brussels Thursday for a summit, expressed their "deepening concerns about Iran's nuclear program."